The present invention relates to an electrophotographic apparatus, facsimile apparatus, printer or similar image forming apparatus and, more particularly, to a sheet separator for separating, after the transfer of a toner image, a sheet carrying the toner image from the surface of a photoconductive element in sliding contact with the element.
It has been customary with an image forming apparatus to transfer a toner image from a photoconductive element, or image carrier, to a sheet contacting it by, for example a bias applied from a charger. After the image transfer, the sheet carrying the toner image has to be separated from the photoconductive element. To insure the sheet separation, a sheet separator is usually held in sliding contact with the surface of the photoconductive element. A sheet separator has been proposed in various forms in the past. For example, Japanese Patent Laid-Open Publication No. 3-33779 teaches a sheet separator configured to obviate noise due to the vibration of the separator contacting a photoconductive element. Japanese Patent Laid-Open Publication No. 3-245137 discloses a sheet separator which does not scratch or otherwise damage the surface of a photoconductive element despite the sliding contact thereof with the element.
On the other hand, a current trend in the imaging art is toward the use of toner having a softening point as low as 80.degree. C. or below in order to lower power necessary for a fixing unit. As to the term "softening point", a flow tester available from Shimazu Seisaku-Sho (Japan) is used for the measurement. Specifically, while a load of 10 kg/cm.sup.2 is constantly applied to toner, temperature sequentially raised by 3.degree. C. every minute. A vessel included in the flow tester is formed with perforations having a diameter of 0.5 mm. Although the volume of the toner sequentially decreases due to the load, it begins to increase when the temperature reaches a certain level. The term "softening point" refers to the temperature at which the volume of the toner begins to increase after the decrease. As the softening point of the toner lowers, filming is more apt to occur on the surface of the photoconductive element due to the loner. Particularly, since the surface of the photoconductive element and the edge of the sheet separator are healed due to friction, toner which enters the interface between them aggravates filming due to the weight of the separator as well as to the temperature. With the conventional sheet separators stated earlier, it is impossible to solve such a toner filming problem.